msm: emac: Corrected wol interrupt handling

As wol interrupt trigger from ephy and there is slight chances
that if emac driver gets multiple wol interrupts and lead to
imbalance of disable irq count.

Enablement of wol interrupt should be atomic to avoid
multiple enablement/disablement of same gpio interrupt
line.

Change-Id: I0efa6547a6d8d9d08aed866e27f69279a083860b
Signed-off-by: Alok Chauhan <alokc@codeaurora.org>